Control: tag -1 moreinfo On Tue, 2016-06-14 at 17:30 -0600, Andrew Patterson wrote: > There is no output in dmesg. > > Changing /proc/sys/fs/aio-max-nr from the default 65536 to 1048576 > seems to help. With this change, I can go up to 256 LUNs (1024 paths) > with no problems. > > I have seen similar issues in earlier versions of multipath-tools.
Thank you for bringing this up, and the pointer. In multipath.conf there was a directive added for something similar. max_fds Specify the maximum number of file descriptors that can be opened by multipath and multipathd. This is equivalent to ulimit -n. A value of max will set this to the system limit from /proc/sys/fs/nr_open. If this is not set, the maximum number of open fds is taken from the calling process. It is usually 1024. To be safe, this should be set to the maximum number of paths plus 32, if that number is greated than 1024. It seems to be inline with what aio-max-nr documentation says. ============================================================== aio-nr & aio-max-nr: aio-nr is the running total of the number of events specified on the io_setup system call for all currently active aio contexts. If aio-nr reaches aio-max-nr then io_setup will fail with EAGAIN. Note that raising aio-max-nr does not result in the pre-allocation or re-sizing of any kernel data structures. ============================================================== Have you tried it with the "max_fds" option set ? -- Ritesh Raj Sarraf | http://people.debian.org/~rrs Debian - The Universal Operating System
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